As well as the games Warriors and Hyrule Warriors (first game Warriors Koei Tecmo made in conjunction with Nintendo), Fire Emblem Warriors is an action title Hack and Slash where you have to overcome numerous groups of enemies with characters from Fire Emblem, so far alone With confirmation of Chrom, although many more characters are expected.
In the conference given in January of 2017 on Nintendo Switch was shown a small trailer of the game, where you can see the representative shield of the saga and then to Chrom grabbing the sword Falchion.
A day later, in the Nintendo Treehouse, where they showed different video game gameplays for the console, it was announced that there would be a Nintendo Direct dedicated to Fire Emblem. This was instantly confirmed by Nintendo's Twitter and it was stated that game information would be presented.
In the said Direct showed a full version of the previous trailer confirming its release date for New Nintendo 3DS and Nintendo Switch, as well as showing some of its gameplay.